Grey squirrels’ problem solving skills help them beat reds in ‘battle of wits’

'Superior behavioural flexibility' could be reason invasive North American species has pushed out UK natives

Grey squirrels fared better than reds in difficult food-extraction tasks set by researchers (Getty Images)

Greater problem-solving abilities may explain why grey squirrels have largely replaced reds as the dominant UK species, according to new research.

Grey squirrels were introduced to Britain in the late 19th century and have all but pushed out the native reds, barring strongholds in Scotland, Cumbria and several islands.

Though red squirrels have inhabited the UK for around 10,000 years, they are now outnumbered by more than 15 to one.

In a study that pitted greys against reds in different tasks, researchers found the newer species had “superior behavioural flexibility” that may have contributed to the success of their UK invasion.

“Many factors have been considered to explain why grey squirrels are more successful when they move into areas where red squirrels live,” said Dr Pizza Ka Yee Chow, an animal behaviour specialist at the University of Exeter.

“These factors include disease resistance and the fact grey squirrels are bigger, but our research shows problem solving could be another key factor for the success of greys.”

While both squirrel species were equally successful in completing an “easy” task – namely opening a transparent lid – the greys were significantly more successful when attempting a “difficult” task, which involved pushing and pulling levers.

In both tasks, successful completion resulted in the squirrels unlocking hazelnuts.

Around 90 per cent of grey squirrels coped with the difficult task, compared to only about 60 per cent of reds.

The scientists said this ability to deal with complicated new problems might be particularly important for invasive species like grey squirrels.

Originally from North America, the greys have therefore evolved to inhabit completely different settings. Their ability to adapt their behaviour and overcome environmental challenges could be key to their success in foreign lands.

Conversely, the inability to extract food with the ease of the greys could put red squirrels at a disadvantage.

However, the researchers did note a glimmer of hope for the reds, as some that successfully completed the trickier task managed to solve it faster in subsequent attempts.

“It is not yet clear whether grey squirrels are born better problem solvers, or whether they work harder because they’re an invasive species living outside their natural environment,” said Dr Chow. “The current stage of our research is to look at this, and the results may give us more insight into the likely future of both species.”

The scientists noted in their paper, which was published in the journal Animal Behaviour, that the ability to problem solve in greys may have resulted from only the craftiest squirrels flourishing in the UK following their invasion.

These findings could have implications for conservationists addressing the threat posed by grey squirrels, as well as other invasive species.

“These results illustrate how investigating animals’ differing cognitive abilities can help us understand important issues in conservation,” said Professor Stephen Lea, another University of Exeter researcher who also contributed to the study.